Indicating device for cross bar switches



y 8, 5 K. A. LUNDKVIST ET AL 2,842,521

INDICATING DEVICE FOR CROSS BAR SWITCHES Filed March 25, 1954 1' N VENTORJ Kmu Hus; Ao/vox wsrfirromvir United States Patent 9 2,842,621 INDICATING DEVICE FOR CROSS BAR SWITCHES Karl Axel Lundkvist and Eric Axel Wiberg, Stockholm, and Arne Kurt Dietsch, Enskede, Sweden, assignors to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Application March 25, 1954, Serial No. 418,726 Claims priority, application Sweden April 10, 1953 3 Claims. (Cl. 179-27.54)

This invention relates to cross bar switches and the purpose of the invention is to provide a switching device for selecting spring sets, which are situated along a selecting bar so that they can be actuated by the operating bars of the cross bar switch.

Many types of switching devices for this purpose are known. A very large number of such switching devices are employed in a telephone exchange, they must be cheap in manufacture; robust and reliable. The switching device according to the invention differs from previously known devices by a lifting bar with a device, which is rotatably mounted on the lifting bar, said lifting bar being common to the contact springs in a spring set, a control spring exerting a torsional moment on said device and pressing the device against a support on the selecting bar, when the selecting bar is not operated and by a particularly shaped portion on said device that is inserted between the lifting bar and the operating bar, when the latter is not energized but the selecting bar is operated so that said support has been removed.

The invention will be described more closely with reference to the annexed drawings.

Fig. 1 shows an isometric view of the upper part of a cross bar switch comprising selecting units which are individually detachable and operating units mounted in a frame.

Figs. 2A to D show fragmentary views of a selecting unit, with the selecting bar not operated, Fig. 2A, and with the selecting bar operated, Fig. 2B.

Fig. 2C shows a spring set seen from the side, the operating bar being removed and Fig. 2D shows the same spring set, the operating bar being inserted.

In Fig. 1, 1 is a frame. On one side of said frame five selecting units 4 are mounted and on the other side there are mounted a number of operating units 2, only one of said last mentioned units, however, being shown on the drawing. Each operating unit comprises a contact bank 3 of insulating material, an end plate 8 and an end plate 7 both screwed to the contact bank. The contact bank 3, which is partly shown in Fig. 2D, carries a number of contact strips 3a, is provided with a hole 3b for each contact spring 16 of the selecting units 4, windows 30 for indicators 18c and holes to mount the contact bank on arms 10a extending from the selecting units 4.

Figs. 2A to C show how the selecting units are arranged. A plate 10 carries a strip 11 of insulating material. The strip 11 has a U-shaped section and carries contact springs 16 for each crossing place between the selecting unit and the operating units 2, and control springs 13 and 19. For each set of contact springs 16, which are associated with the same crossing place, there is provided a common lifting bar 17 and a selecting member 18, which is rotatably mounted on the lifting bar. A selecting bar 12 and an electromagnet 14 are common to the spring sets shown. The selecting bar 12 suspended by means of the spring 13 and is drawn downwards by the armature 15 of the electromagnet when selecting bar 12 is shown pulled downwardly,

2,842,621 Patented July 8, 1958 2 the magnet is operated. The selecting bar 12 and the selecting members 18 are coupled by noses 12a on the bar 12 underlying each selecting member 18.

In Fig. 2A, the magnet 14 is shown as being released and the selecting bar 12 is held in a lifted position by the spring 13. The upper spring set 16 is not energized whereas the lower one is energized by an operating bar 5'.

In Fig. 2B the same spring sets are shown. The it being assumed that the magnet 14 has attracted its armature 15. The spring set 16 at the top of Fig. 2A, its selecting member 18 and the operating bar 5 are all in their initial positions. Hence, operating bar 5 can move upwardly without coming in contact with the selecting member 18 or the lifting bar 17. The selecting member 18 rests against the lifting bar 17 and against nose 12a on the selecting bar 12 and is kept pressed against its points of support by means of a spring 19.

When the electromagnet 14 attracts its armature 15, the selecting bar 12 is drawn downwardly, whereby the selecting member 18 turns about its point of suspension on the lifting bar 17 by the pressure of the spring 19 and moves into the position shown at the top of Fig. 213, if the operating bar 5 is not energized. The lower, wedge-shaped part 18b of the selecting member protrudes between the lifting bar 17 and the operating bar 5. The upper side of the part 18b is circular with its centre in the point of suspension of the selecting member. Between the lifting bar 17 and the lower part 18b of the selecting member 18 there is only a small space, merely determined by the accuracy of manufacture. When the operating bar 5 is energized it will lift the selecting member 18, the lifting bar 17 and the contact springs 16 into the position shown at the bottom of Fig. 2A. As a result, the contact springs 16 move into contact with the contact strips 3a in the contact bank 3. The indicator is lifted in such a way that it will be visible through the window 3c on the contact bank 3. The point of the indicator 180 is painted white so that it is easily seen from the front side of the cross bar switch.

If the operating bar 5 is energized, when the selecting bar 12 is lowered and the selecting member 18 is turned, the lower part 18b of the selecting member will rest against the edge of the operating bar in the manner shown at the bottom of Fig. 2B.

When the selecting bar 12 is moved back to its initial position, the selecting member 18 will also return to its initial position if the spring set 16 has not been actuated by the operating bar 5. If the spring set 16 has been lifted by the operating bar 5 the nose 12a of the selecting bar will not come in contact with the indicating device 18.

The selecting member 18 may be made of metal or insulating material. A metal member has the advantage that is part 18b, which rests against the selecting bar and is shown at the bottom of Fig. 2B, may be bent to adjust the position of the selecting member relative to the operating bar 5.

We claim:

1. In a switching device of the cross bar type wherein sets of contact springs and coacting stationary contacts are disposed in a crossing but normally disengaged relationship, a common selecting bar movable between an operated position and a non-operated position and having a support portion laterally extending therefrom, an operating bar for each set of contact springs movable between an operated position and a non-operated position, a lifting bar for the contact springs in each set to lift the latter from the disengaged relationship into an engaging relationship, a selecting member for each set pivotally connected to the respective lifting bar, a yieldable means coacting with each selecting member for 3; pivoting the latter toward engagement with said support portion, said selecting member having a wedge shaped extension protruding between the lifting bar and the operating bar in engagement with the latter in a first pivotal position of the selecting member and withdrawn therefrom in a second pivotal position of the selecting member, said support portion retaining the selecting member in its first position in the non-operated position of the selecting bar and releasing the selecting member for movement into its second pivotal position by the action of the yieldable means upon actuation of the selecting bar, said lifting bar and said extension being movable into a position abutting against said operating bar upon operation of the selecting bar and the operating bar when actuated lifting said contact springs by the lifting bar through the agency of said extension.

2. A switching device according to claim 1, wherein said selecting member is a lever formed with a groove seated upon one end of said lifting bar, said seating groove constituting the fulcrum of the selecting member, and the other end of the lifting bar facing said operating bar and being separated therefrom by a gap permitting entry of said wedge shaped extension.

3. A switching device according to claim 1, wherein said wedge shaped extension is made of bendable material to permit adjustment of the selecting member relative to the operating bar.

References Cited in the file of this patent UNITED STATES PATENTS 2,362,551 Harrison Nov. 14, 1944 2,598,085 Vidgren et al. Aug. 27, 1952 2,615,095 Graybill et al. Oct. 21, 1952 2,664,468 Montchausse Dec. 29, 1953 2,686,226 Montchausse Aug. 10, 1954 

